The present invention relates to a coder apparatus for performing compression of a video signal and/or audio signal and recording the resultant data on a storage medium such as a hard disk or optical disk and, more particularly, to a method of inserting an editable point when part or all of coded data is to be connected to another coded data, and a coder apparatus using the same.
In general, image signals output from a video camera are independent in units of frames regardless of whether they are applied to commercial use/home use or analog recording/digital recording. For this reason, so-called cut and paste editing for image signals in units of frames is relatively easy to perform.
In contrast to this, according to MPEG2 as international standards of a video/audio coding scheme which is widely used for read-only optical disks such as DVD-ROMs, digital broadcasting, and the like, the numbers of generated bits are adaptively assigned to the respective frames and hence vary in both constant bit rate coding and variable bit rate coding to improve the correction efficiency. In addition, since interframe prediction is used, it is generally not easy to perform cut and paste editing for coded data in units of arbitrary frames.
According to some method, therefore, in video coding based on the MPEG2 standards, to perform correct editing, closed GOPs that inhibit interframe prediction at the GOP boundaries are used to perform editing in units of GOPs (Group of Pictures) each consisting of a plurality of frames, thereby allowing random access. To perform continuous reproduction without any seams between different GOPs and to prevent transmission/receive buffers for coded data from underflowing or overflowing, connection must be performed to satisfy the VBV (Video Buffering Verifier) conditions. If, however, the GOP length is decreased and the VBV conditions are satisfied at the same time to increase the number of random access points so as to increase the degree of freedom in editing, the coding efficiency decreases.
As described above, in conventional video coding based on the MPEG2 standards, as the degree of freedom in editing such as cut and paste editing in units of frames increases, the coding efficiency decreases.